Patent GB-985842-A (GB)
Title: Separation of olefins from aluminium alkyls
Inventor: CARTER WILLIAM BRUCE
IPC: C07F5/06
Filed: 1963-02-28
Abstract: <PICT:0985842/C2/1> A mixture of C2- 4 trialkyl aluminium and at least one a -olefin which is difficultly separable by distillation, is extracted with a 1 : 1 complex of a C2- 4 trialkyl aluminium and an alkali metal fluoride to give a complex enriched with trialkyl aluminium and a raffinate of olefins.  In one embodiment (Fig. 1) triethylaluminium and a solvent are fed to growth reactor 5 at an elevated temperature together with recycled triethyl aluminium 6 and ethylene 8 to give a growth product which is passed to reactor 11. Displacement reactor 11 containing a Ni catalyst is fed with ethylene at 12 and yields a mixture of a -olefins, triethyl aluminium and solvent which enters distillation column 15.  Olefins of 10 C atoms and under are distilled off at 16 while the aluminium compound and C12 and heavier olefins pass to distillation column 19. Olefins heavier than C12 leave at 22 while the mixture of triethyl aluminium and dodecene enters column 21 and is mixed with a 1 : 1 complex of sodium fluoride and triethyl aluminium from line 26.  The raffinate is withdrawn through line 27 and the extract is discharged at 28. Triethyl aluminium is introduced at the bottom of the column through line 29 to strip the extract of any raffinate before it is passed to pyrolyser 31 where it yields the 1 : 1 complex and triethyl aluminium which are both recycled by lines 25 and 33 respectively.  The raffinate is treated with dilute sulphuric acid at 35 to hydrolyse any remaining complex and the raffinate, i.e. dodecene, is discharged at 37. In alternative embodiments (Figs. 2 and 3, not shown) the second distillation column and the use of triethyl aluminium to strip the extract of raffinate, are dispensed with, a single stage extraction is used and a raffinate of C12 and heavier olefins obtained.  Other starting materials may be propylene, butene and tripropyl or tributyl aluminium, while potassium fluoride may be used in the complex.  The solvent may be a paraffin, cycloparaffin or aromatic hydrocarbon, e.g. iso-octane, cyclohexane, benzene or xylene. The catalyst for the displacement reaction may be a cobalt, palladium or iron compound, but preferably a nickel compound, e.g. finely divided Ni, Raney Ni and nickel acetylacetonate or naphthenate.  The examples show that removal of all olefins boiling below that which is difficultly separable, is necessary, otherwise the complex cannot be separated from the mixture.  Reference has been directed by the Comptroller to Specification 779,874.ALSO:A mixture of C2- 4 trialkyl aluminium and at least one a -olefin which is difficultly separable by distillation is extracted with a 1 : 1 complex of a C2- 4 trialkyl aluminium and an alkali metal fluoride to give a complex enriched with trialkyl aluminium and a raffinate of olefins.  In one embodiment (Fig. 1) triethyl aluminium and a solvent are fed to growth reactor 5 at an elevated temperature together with recycled triethyl aluminium 6 and ethylene 8 to give a growth product which is passed to reactor 11. Displacement reactor 11 containing a Ni catalyst is fed with ethylene at 12 and yields a mixture of a -olefins, triethyl aluminium and solvent which enters distillation column 15. Olefins of 10 C atoms and under, are distilled off at 16 while the aluminium compound and <PICT:0985842/C4-C5/1> C12 and heavier olefins pass to distillation column 19. Olefins heavier than C12 leave at 22 while the mixture of triethyl aluminium and dodecane enters column 21 and is mixed with a 1 : 1 complex of sodium fluoride and triethyl aluminium from line 26.  The raffinate is withdrawn through line 27 and the extract is discharged at 28.  Triethyl aluminium is introduced at the bottom of the column through line 29 to strip the extract of any raffinate before it is passed to pyrolyser 31 where it yields the 1 : 1 complex and triethyl aluminium which are both recycled by lines 25 and 33 respectively. The raffinate is treated with dilute sulphuric acid at 35 to hydrolyse any remaining complex and the raffinate i.e. dodecene, is discharged at 37.  In alternative embodiments (Figs. 2 and 3, not shown), the second distillation column and the use of triethyl aluminium to strip the extract of raffinate, are dispensed with, a single stage extraction is used and a raffinate of C12 and heavier olefins obtained. Other starting materials may be propylene, butene and tripropyl or tributyl aluminium, while potassium fluoride may be used in the complex.  The solvent may be a paraffin, cycloparaffin or aromatic hydrocarbon, e.g. iso-octane, cyclohexane, benzene or xylene. The catalyst for the displacement reaction may by a cobalt, palladium or iron compound but preferably a nickel compound, e.g. finely-divided Ni, Raney Ni and nickel acetylacetonate or naphthenate.  The examples show that removal of all olefins boiling below that which is difficultly separable, is necessary otherwise the complex cannot be separated from the mixture.  Reference has been directed by the Comptroller to Specification 779,874.